1. Field of the Invention
The present invention relates to a printer having functions of recording on an integrated roll paper, then cutting the roll paper by a cutter, and discharging the cut paper to an exterior of the printer. The present invention also relates to a cut paper discharge mechanism used for such a printer, and to a paper jam prevention method used in such printer.
2. Description of the Related Art
Generally, this type of printer has a structure in which a thermal head, a cutter unit, and a discharge port are arranged in a vertical direction. With such an arrangement, a paper is discharged through a paper passage extending in a vertical direction from the cutter unit, which is disposed at a lower portion of the printer, toward the discharge port, which is disposed at an upper portion of the printer. The roll paper is integrated into the printer. The thermal head or the like prints on the roll paper. The printed roll paper is cut by the cutter unit. The cut paper is discharged through the discharge port to above the discharge mechanism. The printer having such an arrangement is widely used for POS terminal devices for issuing receipts and automatic dispensers for issuing coupons or tickets.
Recently, many printers have employed an arrangement for discharging a printed roll paper in a fully cut state, called a full-cut paper. A paper jam is problematically caused in a printer in which full-cut papers are discharged to above a discharge mechanism.
Cutter units capable of preventing a paper jam have been proposed in Japanese laid-open patent publications Nos. 2001-246593 (Patent Document 1) and 2001-293684 (Patent Document 2).
The cutter unit disclosed by Patent Document 1 includes a stationary blade member having a stationary plate blade and a movable blade member having a movable plate blade. When the movable blade is reciprocated with respect to a paper passage defined between the stationary blade and the movable blade, a roll paper is cut by the blades. The full-cut paper is discharged through a discharge port. The cutter unit disclosed by Patent Document 1 introduces an edge of a full-cut paper cut by the movable blade into a groove portion provided in the stationary blade with use of the movable blade so as to prevent the full-cut paper from falling into a paper passage in the printer.
The cutter unit disclosed by Patent Document 2 controls a position of a movable blade so as to dispose the movable blade at a standby position at which the movable blade covers a paper inlet, which forms a paper passage, after cutting a roll paper. Specifically, when supply of the roll paper is started, the movable blade is moved from the standby position so as to open the paper inlet. When the roll paper is supplied by a predetermined length, the movable blade is moved to the standby position. Then, the roll paper is cut, and the supply of the roll paper is stopped.
Thus, the cutter units disclosed by Patent Documents 1 and 2 prevent falling of the full-cut paper or re-cutting of the full-cut paper by supporting the edge of the full-cut paper on the stationary blade or by controlling a position of the movable blade in the cutter unit. However, Patent Documents 1 and 2 fail to disclose an improvement of an arrangement in portions other than the cutter unit to prevent falling of a full-cut paper or the like.
Meanwhile, a paper passage extending from a cutter unit to a discharge port may be inclined in order to prevent falling of a full-cut paper. According to experiments conducted by the inventors, when a paper passage extending from a cutter unit to a discharge port was inclined, it was necessary to consider that a degree of curl of a full-cut paper varied according to a variation of a radius of curvature of the roll paper (a roll diameter of the roll paper). Specifically, the roll paper has a large radius of curvature (i.e., a small curvature) near its beginning. As a result, full-cut papers have a low degree of curl. The roll paper has a small radius of curvature (i.e., a large curvature) near its dead end so as to produce a strong tendency to curl. Accordingly, a degree of curl of full-cut papers becomes high.
More specifically, if a full-cut paper having a low degree of curl is supplied from a cutter unit through an inclined paper passage into a discharge port, then the full-cut paper falls onto a portion of the cutter unit through the paper passage. Accordingly, the full-cut paper is prevented from falling into a paper passage in the printer as with the cutter units disclosed by Patent Documents 1 and 2.
However, when the paper passage was inclined, a lower end of the full-cut paper was not supported by a portion of the cutter unit if the full-cut paper has a high degree of curl. That is, the lower end of the full-cut paper is separated from the portion of the cutter unit. It was found that the full-cut paper fell off from the inclined paper passage into a paper passage in the printer.